This invention relates to sails and sailing systems generally, and in particular, to an improved sail system that permits the sailor to directly control the degree of sail camber or curvature while sailing.
Heretofore the free sail systems commonly employed in board sailing, have relied on downhaul and outhaul tensioning of the sail at the time of rigging for the setting of sail camber. Once rigged, the sailor's manipulation of the sail is limited to varying sail angle of attack, sail heel, and rake.
The additional ability to alter and control sail camber while under way is desired. For instance, a less cambered sail is preferable while sailing close to the wind whereas a more cambered sail maximizes thrust and speed when sailing off the wind. For sailboard wave jumping, using a more cambered sail obtains a higher jump, but may not be suitable for sailing prior to and after jumps. When sailing in variable wind conditions, it is desirable to use less camber during wind gusts.
A primary object of the present invention is to provide a sail system which allows the sailor to vary the degree of sail camber while underway.
There are presently available devices which effect small changes in sail camber when sailing vehicles are underway. Camber inducers found on slalom free sail systems, for example, act to transfer loads from the mast to the batten enhancing batten bend and producing a more camber stable sail. However wind speed and mast and batten stiffness determine the degree of camber stability such devices are capable of producing.
A second object of the present invention is to provide a sail system which allows the sailor to vary the amount of sail camber while underway, irrespective of wind conditions.
Prior art efforts to allow sailors to vary sail tension while sailing have included the tensioning of outhaul and downhaul using lines, worm gears or hydraulic pumps. Such methods involve significant lag time to actuate and require the sailor to release at least one hand from the boom. Varying sail camber reflexively in response to wind gusts cannot be effected using these prior art methods.
It is a further object of the present invention to provide a sail system which allows the sailor to vary sail camber immediately, with little effort and without requiring the sailor to release his or her hands from the sail controls.
Most available sail systems have a boom which attaches to the clew of the sail. This conventional sail configuration causes the draft to move aft, and the LE portion of the sail to collapse, whenever the sail is held at a low angle of attack in moderate or stronger winds. Sails are held at low angles of attack, for example, when counterbalancing moderate or heavy wind conditions. Thus as wind speed increases the sail draft continues to move aft while the luff portion collapses, until the sail becomes uncontrollable.
It is a further object of the present invention to provide a sail system wherein the sailor can maintain the draft in the LE portion of the sail and release the aft portion of the sail during low angles of attack and despite increasing wind conditions.
Presently, sailors select sail sizes depending upon wind conditions. Small sized sails are employed during high wind conditions, and larger sizes for light winds. In variable wind conditions, sailors often find themselves either over or underpowered or both.
It is a further object of the present invention to provide a sail system which may be employed efficiently in variable wind conditions such that the sailor has better sail control during wind gusts, yet is not underpowered in moderate wind.
Conventional sailboards employ a wishbone boom firmly attached to a mast. This traditional configuration maintains the alignment of the sail tack and head directly behind the mast and causes the aerodynamics of the sail head and tack regions to behave less efficiently compared with the remainder of the sail luff.
It is a further object of the present invention to provide a sail system for sailboards having increased aerodynamic efficiency along the head and tack regions by virtue of demonstrating a more continuous camber along its luff region.
Prior art sails employed in sailboarding tend to roll, rather than glide, when wave jumping. This roll tendency is caused by the sailor's inability to place his or her body mass beneath the sailing system's center of effort during jumping activities. One attempt to prevent the roll during sailboard jumping is disclosed in Nishimura U.S. Pat. No. 4,625,671, It is a further object of the present invention to disclose an alternative method for promoting balanced glides during sailboard wave jumping activities.
Sailboard free sail systems used in wave sailing often encounter extreme forces particularly when down in the waves. Wave pressure on the sail, which is held tautly between the boom and mast, subject the mast to great stress to the point of breaking. It is a further object of the present invention to provide a more flexible and forgiving sail system less subject to mast breakage when dropped in large wave conditions.
These and other objects are accomplished in the present invention, a camber control sail system comprising a sail, a mast, and a set of camber control handles extending from each side of the sail. The sail is attached to the mast along its luff portion. One camber control handle extends from the mast, a second handle extends from the sail aft of the first handle. In most embodiments, one or more control battens traverse the sail at a level intersecting the control handles.
The camber control sail system allows the sailor to control sail camber instantaneously, without releasing control apparatus, in a variety of wind conditions. Accordingly, the sailor can adjust sail camber for wind gusts irrespective of angle of attack, as well as for wave jumping and other maneuvers. The camber control sail system facilitates a more uniform camber along the entire luff portion of the sail contributing to the aerodynamic efficiency of the head and tack regions. The present invention, when employed on sailboards, promotes a controlled glide during wave jumping and renders mast breakage less likely in large wave conditions. Further objects and advantages of this invention will become apparent from a consideration of the drawings and ensuing descriptions.